A large scale integrated circuit (LSI) mounted on a printed circuit board generates noise, and an interconnection pattern radiates noise electromagnetic waves. Also, when the interconnection pattern receives noise such as static electricity and the like, the noise may be a cause of a malfunction in the LSI. In order to reduce the amount of radiation of electromagnetic waves and malfunctions caused by noise, EMC countermeasure design is conducted, and there are EMC design check systems used for checking design quality. The term “EMC design check” means check performed to detect whether or not there is a net from which a great amount of electromagnetic wave is likely to be radiated. An EMC countermeasure is performed on the net detected by the check to reduce the amount of radiated electromagnetic wave, thus reducing the occurrence of a malfunction of the LSI.
In the related art, each net relating to EMC is scored for various elements on the basis of position coordinates and product information as information of computer aided design (CAD), and prioritizing is performed using a total score. For example, as illustrated in FIG. 1, when 1000 nets, that is, NET 001 to NET 1000, are checked for five elements of Check 1 to Check 5, 5000 times (5×1000=5000) of checks are performed. Then, points are given, for example, such that, if there is no problem (or a check is passed) in Check 1 to Check 5, 0 points are given, if there is a problem in Check 1, 10 points are given, if there is a problem in Check 2, 5 points are given, if there is a problem in Check 3, 10 points are given, if there is a problem in Check 4, 7 points are given, and if there is a problem in Check 5, 10 points are given. Thus, for example, as illustrated in FIG. 2, results of 5000 checks are registered in a table, and the total of scored points (an evaluation score) is calculated for each net. When nets are arranged in a descending order of the evaluation score, a net on which a countermeasure is to be performed may be selected. However, even when an evaluation score is lower than a threshold, there might be cases where, if the evaluation score is lower only by a few points than a threshold, it is determined that a countermeasure is to be performed on the evaluation score. Thus, there might be cases where net selection may not be performed in a uniform manner.
In the above-described example, the number of nets is only 1000. However, in actual cases, checks are performed on even more nets, and thus, a time spent for an entire check is disadvantageously long.
Japanese Laid-open Patent Publication No. 2010-257098, Japanese Laid-open Patent Publication No. 06-325109, Japanese Laid-open Patent Publication No. 2011-8664, Japanese Laid-open Patent Publication No. 2008-181353, Japanese Laid-open Patent Publication No. 2002-32428, Japanese Laid-open Patent Publication No. 2005-223120, and Japanese Laid-open Patent Publication No. 2006-172370 are examples of the related art.